LABOR Leader Bryan Green has accused the state Liberals of delaying a new mine and criticised them for not seeking court costs from Save the Tarkine.

But the Liberals say they were unable to pursue the environment group for costs from recent Federal Court proceedings relating to Venture Minerals' planned iron ore mine near Tullah because of dealings when Mr Green was deputy premier.

They also questioned his understanding of mine approvals processes.

Mr Green said the Abbott government was holding up Mancala Resources' planned lead and zinc mine at Guildford, despite it not being opposed by environmentalists.

He claimed the Liberals had broken a promise to back mining projects.

"First, they refused to pursue costs against Save the Tarkine over its vexatious appeal against Venture Minerals," Mr Green said.

"Now the federal Liberal government is perversely standing in the way of Mancala's Burns Peak project when environment groups have effectively given it the green light."

Mr Green said the state government should stand up to the Abbott government to get the Mancala development going.

State Resources Minister Paul Harriss said: "Bryan Green was the minister when the state government became a party to the Federal Court case relating to Venture's Riley mine."

"At that time, the government was added as an additional respondent with the consent of the other parties and gave an undertaking that it would not pursue costs."

Venture and the Commonwealth are pursuing costs from the case, which could potentially give the environment group a $200,000 hit.

Mr Harriss said Mr Green knew, or should know, "that there is a bilateral agreement between the state and federal governments for the assessment of mining operations".